I've changed the same sized tire, 50 gallons of fluid in each alone with nothing but the nut removing device, a 2x4 block of wood and a crow (wrecking) bar....about 3' long, popular at any construction supplier...Lowes, Home Depot, HF.
The key is keep the tires vertical, meaning no more than a few degrees of leaning. I figure where I am going to roll them (concrete floor) and prop up before I remove them.
I made a stand out of 2x2 square tubing that I put under the drawbar where it attaches at the front end. I made it so that I would need a couple of 2x4 blocks to barely get the tires off the floor...like less than an inch. Now we are at the point where the tires are off the floor and pretty much balanced.
Next off come the nuts with an impact tool. The wheel is usually rusted to the axle so I beat on the rim with a 4# short handle sledge moving from side to side, paying attention to be ready to support the tire (with my unused hand) when it breaks loose.
Next comes the prybar and the 2x4....2x4 about 2-3" away from the side of the tire and with one hand holding the top of the tire (to keep it from falling over) the other hand (in short up and down movements), walks the wheel off the notched axle. Now the tire is on the ground adjacent to the axle...like 1-2" sort of thing.
I then grasp both sides of the tire, at about the 2 and 10 O'clock positions and walk the tire back from the wheel, by rolling a couple of inches, turning and rolling back the other way, back and forth till the VERTICAL wheel/tire assy is away from the tractor and can be rolled away.
Once you remove one wheel, the tractor tilts over on to the other side...amount depends on how much the support member holding the tractor off the ground allows the tractor to tilt.
Repeat the removal process and immediately roll the tire to the other side, always keeping it vertical.
You walk the tire over to the axle the same way you removed them just in reverse order, use the pry bar as you did to line up/elevate the tire and push it onto the studs and get a couple of nuts on it. Finish replacing the nuts and impact them in place with an X criss cross pattern.
Get the other tire and repeat the process. Done deal! Takes half an hour or so.